OCT Angiography (OCTA) of Macular Telangiectasia Type 2

Abstract

 

Purpose

 

To evaluate the microvasculature of the central macula in eyes with macular telangiectasis type 2 (MacTel2)<br /> using swept-source (SS) and spectral-domain (SD) optical coherence tomography (OCT) angiography.

 

Methods

 

Subjects were enrolled in a prospective, observational study and evaluated using a high-speed 1050 nm<br /> SS-OCT prototype system (100,000 kHz) and a 840 nm SD-OCT prototype system (68,000 kHz). SS-OCT<br /> angiography was performed using a 3X3mm raster scan pattern centered on the fovea. In the transverse scanning direction, a single B-scan was comprised of 300 A-scans. Four consecutive B-scans were performed at each fixed position before proceeding to the next transverse position on the retina. A total of 300 B-scan positions located 10 μm apart over a 3 mm distance were sampled. SD-OCT angiography was performed using a 3X3mm and 6X6mm raster scan pattern. In the 3X3 raster scan, four consecutive B-scans, each comprised of 245 A-scans, were performed in the transverse scanning direction. In the 6X6 raster scan pattern, the transverse scanning direction was comprised of two consecutive B-scans, each of 350 A-scans. A total of 245 B-scan positions were located 12.4 μm apart over the 3 mm distance, and a total of 350 B-scan positions were located 17.1 μm apart over the 6 mm distance. Algorithms segmented the retina into three layers; an inner retinal layer, a middle retinal layer, and an outer retinal layer. The vascular distribution in each layer was depicted as an en face image. En face OCT angiographic images were compared to early and late phase fluorescein angiography (FA) images.

 

Results

 

OCT angiography imaging was performed on 35 subjects (67 eyes) with MacTel2. In all MacTel2 eyes, an abnormal microvasculature was detected. In early stages of MacTel2, these abnormal vessels appeared to reside predominantly in the middle retinal layers or deep capillary plexus. The earliest manifestations included dilation and truncation of the microvasculature in the temporal juxtafoveal location. As the disease progressed, all retinal layers became involved and demonstrated abnormal vascular patterns.

 

Conclusions

 

OCT angiography can be performed with both SS-OCT and SD-OCT instruments and provides rapid, non-invasive, high-resolution, depth-resolved images comparable to or even better than conventional fluorescein<br /> angiography in eyes with MacTel2.